A typical aircraft has landing gear comprising a plurality of wheeled landing gear assemblies which support the aircraft when it is on the ground. The landing gear assemblies are used to control the movement of the aircraft during ground manoeuvres such as landing, taxiing and take off. A typical large jet-powered aircraft includes a steerable nose landing gear (NLG) assembly located towards the front of the fuselage and a plurality of main landing gear (MLG) assemblies (also known as bogies) located rearwards of the NLG assembly and distributed laterally about the aircraft longitudinal axis. The MLG assemblies typically each include one or more actuators which are operable to provide a braking force and/or driving force to decelerate and/or accelerate, respectively, the wheels of that MLG assembly.
The movement of such an aircraft on the ground, e.g. during ground taxi manoeuvres, is determined by control commands issued from the cockpit. To achieve these control commands, the landing gear is required to achieve a particular longitudinal force demand. The present invention is concerned with the control of the wheel braking and/or driving actuators to achieve those demands.